package net.oschina.j2cache.redis;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import net.oschina.j2cache.CacheException;
import net.oschina.j2cache.Level2Cache;
import redis.clients.jedis.BinaryJedis;
import redis.clients.jedis.BinaryJedisCommands;
import redis.clients.jedis.MultiKeyBinaryCommands;
import redis.clients.jedis.MultiKeyCommands;

/**
 * Redis 缓存操作封装，基于 region+_key 实现多个 Region 的缓存（
 * 
 * @author Winter Lau(javayou@gmail.com)
 */
public class RedisGenericCache implements Level2Cache {

	private String namespace;
	private String region;
	private RedisClient client;

	/**
	 * 缓存构造
	 * 
	 * @param namespace
	 *            命名空间，用于在多个实例中避免 _key 的重叠
	 * @param region
	 *            缓存区域的名称
	 * @param client
	 *            缓存客户端接口
	 */
	public RedisGenericCache(String namespace, String region, RedisClient client) {
		if (region == null || region.isEmpty()) {
			region = "_"; // 缺省region
		}

		this.client = client;
		this.namespace = namespace;
		this.region = _regionName(region);
	}

	/**
	 * 在region里增加一个可选的层级,作为命名空间,使结构更加清晰 同时满足小型应用,多个J2Cache共享一个redis database的场景
	 *
	 * @param region
	 * @return
	 */
	private String _regionName(String region) {
		if (namespace != null && !namespace.isEmpty()) {
			region = namespace + ":" + region;
		}
		return region;
	}

	private byte[] _key(String key) {
		return (this.region + ":" + key).getBytes();
	}

	@Override
	public byte[] getBytes(String key) {
		try {
			return client.get().get(_key(key));
		} finally {
			client.release();
		}
	}

	@Override
	public List<byte[]> getBytes(Collection<String> keys) {
		try {
			BinaryJedisCommands cmd = client.get();
			if (cmd instanceof MultiKeyBinaryCommands) {
				byte[][] bytes = keys.stream().map(k -> _key(k)).toArray(byte[][]::new);
				return ((MultiKeyBinaryCommands) cmd).mget(bytes);
			}
			return keys.stream().map(k -> getBytes(k)).collect(Collectors.toList());
		} finally {
			client.release();
		}
	}

	@Override
	public void setBytes(String key, byte[] bytes) {
		try {
			client.get().set(_key(key), bytes);
		} finally {
			client.release();
		}
	}

	@Override
	public void setBytes(Map<String, byte[]> bytes) {
		try {
			BinaryJedisCommands cmd = client.get();
			if (cmd instanceof MultiKeyBinaryCommands) {
				byte[][] data = new byte[bytes.size() * 2][];
				int idx = 0;
				for (String key : bytes.keySet()) {
					data[idx++] = _key(key);
					data[idx++] = bytes.get(key);
				}
				((MultiKeyBinaryCommands) cmd).mset(data);
			} else {
				bytes.forEach((k, v) -> setBytes(k, v));
			}
		} finally {
			client.release();
		}
	}

	@Override
	public boolean exists(String key) {
		try {
			return client.get().exists(_key(key));
		} finally {
			client.release();
		}
	}

	/**
	 * 性能可能极其低下，谨慎使用
	 */
	@Override
	public Collection<String> keys() {
		try {
			BinaryJedisCommands cmd = client.get();
			if (cmd instanceof MultiKeyCommands) {
				Collection<String> keys = ((MultiKeyCommands) cmd).keys(this.region + ":*");
				return keys.stream().map(k -> k.substring(k.indexOf(':') + 1)).collect(Collectors.toList());
			}
		} finally {
			client.release();
		}
		throw new CacheException("keys() not implemented in Redis Generic Mode");
	}

	@Override
	public void evict(String... keys) {
		try {
			BinaryJedisCommands cmd = client.get();
			if (cmd instanceof BinaryJedis) {
				byte[][] bytes = Arrays.stream(keys).map(k -> _key(k)).toArray(byte[][]::new);
				((BinaryJedis) cmd).del(bytes);
			} else {
				for (String key : keys) {
					cmd.del(_key(key));
				}
			}
		} finally {
			client.release();
		}
	}

	/**
	 * 性能可能极其低下，谨慎使用
	 */
	@Override
	public void clear() {
		try {
			BinaryJedisCommands cmd = client.get();
			if (cmd instanceof MultiKeyCommands) {
				String[] keys = ((MultiKeyCommands) cmd).keys(this.region + ":*").stream().toArray(String[]::new);
				if (keys != null && keys.length > 0) {
					((MultiKeyCommands) cmd).del(keys);
				}
			} else {
				throw new CacheException("clear() not implemented in Redis Generic Mode");
			}
		} finally {
			client.release();
		}
	}

	@Override
	public long size() {
		return 0;
	}

}
